Stared WKHTMLTOPDF branch

Updated common.txt to include pywkher and other dependencies
Added /pdf url for sample pdf
Added pdf.html as the sample pdf to be converted
Initial pdf template
Added method that cleans filenames
Download button works (kind of)

Select items (using checkbox), it will show you the pdf of the first.
Sleepy coding. Probably made lots of stupid decisions.
But it works now. So yay.
Merged dev for bug fix
Fixed some consistency problems with pdfs
Set pdf.py to use environment's wkhtmltopdf binary
Merge branch 'wkhtmltopdf' into dev

Make sure to set up your WKHTMLTOPDF_CMD environment variables for
local development
Merge branch 'dev' of github.com:MitchelCabuloy/Syllia into dev